Oil-fuse.



L. W. DWNES.

OIL FUSE.v

APmcATaoN F|LEn1uLY17,1912. RENEWED FEB. 26.1914.

l 203,3 1 6. Patented Oct. 31, 1916.

2 SHEETS-SHEET l.

L. W. DOWNES.

OIL FUSE.

MPL10/111011 r|LED1uLY17.1912. RENEwEu 155.216.1914.

1 203 316. 111116111911 001.. 31, 11116. 5 78 2 SHEETS-SHEET 2.

LOUISW. DOWNES, 0F PROVIDENCE, RHODE ISLAND.

OIL-FUSE.

Specification of Letters Patent.

Application led July 17, 1912, Serial No. 710,044.

To'all whom t may concern e Be it 'known vthat I, Louis W. DowNEs, ofProvidence, Rhode Island, have invented a new and useful Improvement inOil-Fuses, which invention is fully set forth in the followingspecification.

Experience has demonstrated that electric fuses of well-known typeswhich have heretofore given satisfactory operation on single phase hightension circuits are not always sure and satisfactory in their opera.-vtion on the more modern poly-phase systems of electric distribution, andhence with such modern systems have come to be regarded as a source ofuncertainty and consequent danger.l

The principal object of the present invention is to provide an electricfuse adapted to serve as a primary and junction cut-out on high tensionpoly-phase circuits such as those of2,500 bolts or more. That object Ibelieve I have attained by the fuse of the present invention which inits operation is Y adapted to break the circuit in oil, tests andexperience with such fuses having yielded satisfactory results underconditions of eX- treme severity and heavy overload.

A further object of the invention is to provide a structure which willprevent the oil in the receptacle or casing from being blown out of saidcasing under conditions that may be frequently encountered, suchdischarge or absence of the oil leaving nothing in thel casing toextinguish the arc that might be formed, as the result of which' therewould be violent arcing with consequent destruction of or injury to thedevice. To illustrate, a condition might exist on a circuit supplyinglights or power whereby the lines had become short circuited at somedistant point, causing immediate blowing of the fuse at the transformer.A lineman going to investigate the trouble might not immediately findthe insert a new fuse. In the absence of provision to meet thecondition, the instant the new fusel is inserted and its connection inthe circuit el'ected-the-trouble still being prcsent-it would be blownby a heavy rush of current through it, and if the cover of thereceptacle had not curely fastened, it would be forced olf and aconsiderable part of the oil immediately blown out of the casing, withthe result that dangerous arcing would take place. To meet such.conditions the fuse of my present cause and proceed to been closed andse Patented Got. 31, 1916.

Renewed February 26, 1914. Serial No..821,318.

invention embodies means whereby the cover ofthe casing must be closedand locked before the newly inserted fuse can be connected between thecircuit terminals within the caslng. As a suitable way of providing forsuch closing and locking of the cover before the circuit is completedthrough the fuse, I have illustrated the employment of a bayonet jointconstruction to be more fully described in detail hereafter. By suchconstruction and the relative arrangement of the fixed terminalsl withinthe casing and the contacts on the fuse carrier Y between which the fuselink is connected, the casing cover with the carrier fixed theretomustbe put in place and then rotated through an.

arc, preferably of approximatelyy 90, before the contacts on the fusecarrier engage the fixed terminals within the casing to complete thecircuit through the fuse link. Hence, even if a new a fuse be insertedin a live circuit-one for instance Which has been crossed by anothercircuit--noA harm can occur to the apparatus or the operator since thereis no opportunity for the oil to be blown out. Preferably the oil levelis somewhat below the top of the oil chamber in the casing to permit ofmovement of the oil on the blowing of the fuse. Experience hasdemonstrated that when such a. fuse is blown under very severeconditions the oil will be driven up against the top of the box withconsiderable force, but will immediately fall back to the bottom of thecasing, any arc that may be formed being promptly extinguishedandburning of the fuse 'terminalsl 2 is a horizontal section on line 2-2of Fig.

l. Fig. 3 is a vertical section on line 3-3 of Fig. 2. Fig. 4 is ahorizontal section on line 4-4 of Fig. 1. Fig. 5 is a fragmentary viewof the fuse carrier and parts thereon. Fig. 6 is a detail sectional viewon line G of Fig. 2. Fig. 7 is a detail sectional vieW on line 7 of Fig.2. Fig. 8 is a detail view of one of the fuse carrier contacts. Fig. 9is a detail view of thefuse link of Figs. 1-5. Fig. 10 is a detail viewof another form of fuse link. Fig. 11 illustrates the fuse link of Fig.`l() applied to a fuse carrier shown in outline, andv Fig. 12 is a viewsimilar to Fig. 11 but. showing the action or other structure. Terminal'conductors 22 vand 23 enter said casing by passing upwardthroughbushings 24, 25, respectively. The conductors make a close litthrough the bushings the openings of which are enlarged 'at the upperend and filled with a suitable oil proof cemen-t 24 such as shellac gumpoured in while liquid. This seals the cable entrances and preventsescape of oil from the casing at these points. rlFhe bushings are ofporcelain or other suitable insulating material and depend throughvertical openings in bulges or pockets 26, 27 at opposite sides of thecasing. Vertical Hanges or ribs 28 positioned at intervals about theexterior surface of the casing serve in the well known way to lextendthe heat radiating i surface and thereby facilitatedissipation of i" theheat developed by the fuse when running under normal conditions ofloadThe casing is made relatively large to contain a liberal volume of oiland dissipation of heat tions.

is such as to avoid ,any possibility of disintegratlon of the oil andinsure a safely low temperature under normal working condi- ()n theinside of the casing the terminal conductors .22 and 23 lead to fixedlspring terminals adapted to coperate with contacts on the fuse carrieras described here- The inner end of conductor 22 is. lsoldered orotherwise electrically connected after.

in a clip 29 which makes electrical contact with one end of a U-shapeterminal 30, the

other end of which is broadened and shaped in the form of a shoe 31adapted to bear against the peripheral surface of the fuse carrier andwhen the latter is rotated to proper position to makeelectrical contactwith one of two contact pieces thereon. Both the clip 29 and theterminal 30 are secured to and supported from the quarter circlearc-shaped block 32 of porcelain or other suitable insulating materialby screws 37,- 38, said block 32 resting at its opposite ends uponshoulders 33, 34 and being secured to said shoulders by screws 35.Between the ,shoulders the block 32 -bridges a recess or pocket 36 intowhich the terminal 30 depends. Inside of the casing the terminal' cable23 leads to similar parts, the description of which need not be hererepeated and to which the reference numerals heretofore mentioned alsoapply.

Thefcasing is partially closed by ring 39 with interposed gasket 40 andheld in place by four screws 4l.

42 is a. cover fitting closely in the central opening of ring 39 andhaving a flange depending about an upwardly projecting neoeie flange onsaid ring 39; an interposed gasket 43 of cork or other suitable materialinsures a tight joint and yields sufficiently to permit themaking of abayonet joint connection between the cover and the ring 39 about to bedescribed. Notches 44, 44, (Fig. 4) at opposite sides of the centralopening through ring 39 admit of the passage of lugs 45, 45 o n thelower edge of the cover 42 until such lugs clear the lower edge of thering 39, whereupon the cover may be rotated to carry the lugs 45 out ofregister with the notches 44 into locking engagement with the under edgeof the ring 39, the parts described thus constituting a bayonet joint.rllhe cover is preferably of cast metal hollowed with a depending studadapted to fit into a central opening in the upper end of a fuse carrier46, thus centering the latter With relation tothe cover. A suitablecement 47 filled intothe cover about the upper end of the fuse carrier46 in a plastic state thereafter hardens and securely fastens the fusecarrier to the cover.

The fuse carrier 46 is preferably of porcelain but may be of othersuitable insulating material. On opposite sides of its lower end, ithasyvertical grooves or channels 48 enlarged at their upper ends toreceive contacts and other parts about to be described. Oneof thesecontacts, illustrated in detail in Fig. 8, consists of a plate 49fitting against and held to' an over-hanging horizontal surface of thefuse carrier by means of screwbolts 50 and 5l passing through openingsin said plate 49; a leg 52 of plate 49 has a rounded o uter surfaceadapted to engage and make electrical contact with the shoe 31 of theterminal 30 when the cover and the -fuse carrier have been rotated intoposition to bring these parts into engagement. A second leg 53 of plate49 bears against an upright surface of the carrier 46 and has an opening54 traversed by a bolt 55 the head of which is secured in a recess inthe fuse carrier by a filling of suitable cement adapted to be appliedin a plastic state and to thereafter harden. A spring 56 fastened to theunderside of plate 4.9 also has an opening traversed by the bolt 55, aknurled nut 57 making screw-threaded engagement with the bolt on theouter side ofspring 56. This arrangement of .parts is duplicated onopposite sides of the fuse carrier and the descrippart of the linkextending across the lower endof saidcarrier.

Two suitable forms of links or fuses for use in this device are thatshown in Figs. 1, 5 and 9, and that shown in Figs. 10, 1l and 12. Theconstruction of the former is as follows :-At `opposite ends it hasnotched copper terminals GO toeach of Which there is riveted andsoldered a copper wire section G1 each of which is in turn riveted andsoldered to a short flat strip section 62, preferably of zinc. Thesestrips 62 are slightly tapered at their opposing ends which arepositioned to terminate a predetermined distance apart and are connectedby a narrower metal strip 63, preferably of Zinc, overlapping the strips62, 62, and joined thereto by solder adapted to melt at a suitably lowtemperature. The Zinc strips G2, (32 as thus.

connected by narrower Zinc strip 63 constitute in effect an ordinar)Tcentrally notched Hat fuse strip or link. As most clearly illustrated inFig. 1 such fuse link is bent in U-shape around the fuse carrier 46 withthe narrow zinc strip 63 and parts of the strips (S2. (52, extendingacross the lower horizontal end of said carrier and the remainingportions of the link extending upward in the channels 4S, 48, atopposite sides of the fuse carrier, the notched terminals G0, (i0, eachengaging its corresponding screw-bolt between the leg 5l and the spring56 and being tightly gripped between such parts vby the tightening ofthe knurled nut 57. In case of excessive current traversing the fuse thetemperature produced is such as to melt the solder connecting the stripG3 to the strips (S2, (32, permitting said'strip (53 to drop to thebottom of the casing 20, thereby opening the circuit. But in case ofgreatly excessivev current, such temperature might be instantlydeveloped as not only to melt the solder joining the strip (33 to thestrips 62, G2, but also melt the strip (53.

The object of the before described construction of fuse link is toovercome difficulty experienced when using an ordinary notched link ofzinc or other similar metal, that of excessive temperature rise in theoil which might ultimately change the characteristies of the oil. Thisdiliiculty might also be overcome by the use of a simple Hat link ofFigs. 10-12, when made up in the following manner z-Two copper or bronzeterminal strips 70, are notched for engagement with the two bolts 55,previously mentioned, and joined by fusible connecting strip 71, theoverlapping ends of the strips 70 and 71 being riveted and solderedtogether.l Strip '71 is of some suitable low melting alloy, notched atits middle in the well-known manner for the purpose of giving the properoverload characteristics. The outer ends of terminals of this link beingof bronze or copper and having a relatively lower resistance. are notheated excessively by the passage of the current through them, while theconnecting strip 71, being of short length and low melting point, doesnot reach a very high temperature; it follows then that the totaltemperature rise in the oil is thus kept at a reasonably low figure. The

outer ends of the strips 70, 70, are bent as shown in Fig. 11, wherebythe forcing of these bent ends to a straight position as' illustrated indotted lines in said Fig. 1 1 and their engagement with the bolts 55between the plates and the springs 5G places said strips 7() under atension tending to cause the lol-fer ends thereof to spring apart orseparate. In operation when an overload softens the fusible strip 71 atits notch, the strips 70, 70 spring apart as illustrated in Fig. 12quickly separating the severed ends of the strip 7l, the actionresembling that of a quick break switch submerged in oil and eliminatingor minimizing any possible formation of an arc upon the opening of thefuse.

v The casing is filled with some suitable oil such as paraiiin ormineral oil, preferably to approximately the level, indicated by theline marked ()il level in Figs. 1 and 3, the action of such oil inpreventing or suppressing the formation of an arc upon the blowing ofthe fuse being well-known. As has already been suggested, when the coverand the fuse carrier are insertedin the casing in such position as topass the lugs 45 on the cover through the notches 44, the contacts 52,52, on the fuse carrier stand in a line approximately transverse to theline of the terminal shoes 81, 31 and hence out of Contact with thelatter; and to bring these parts into engagement or electrical contactthe cover must be rotated through an arc of a i )roximatelv 90o whichserves to carr the lugs 45 out of register with the notches 4-1 andhence into locking engagement with the under edge of the dependingflange around the central opening through the ring 39. This insureslocking of the cover in place before the electric circuit is establishedthrough the fuse link and its connections mounted on the fuse carrier46. The action is reversed upon the removal of the cover 12 and the fusecarrier 4G, and if at the time of such removal the fuse link has notbeen disrupted and the, circuit is complete therethrough, the opening ofthe circuit will take place between the contacts 52 and the terminalshoes 3l both of which are at the time submerged in oil; consequentlythere will be no material arcing.V

To relieve possible excessive pressure within the casing due totheformation of vapor when the fuse acts under excessive overcharge ofcurrent, a relief valve is provided. As shownA it consists of a tube 75threaded into an opening in the ring 39 and closed at its outer end by aplug 7 6. A stem 7 7 working through an opening in said plug carries atits outer end a cap 78 and at its inner end a piston 7). In the normalposition, the piston closes vent openings S0 through the side of tube 75and cap 7 8 tits down over the outer end of the tube, ex-

&

cessive pressure Awithin the casing forces the piston outward and opensthe vents for the escape of gas or vapors. The cap 7 8 lsheld in itslifted position by the'friction of the piston, thus serving as anindicator showing that the fuse has operated.

. What ll claim is:

1. The combination of a receptacle orcasing containing a suitable arcsuppressing liquid; circuit terminals within said receptacle; a coverand fuse-carrier for closing the receptacle; locking means for securingthe cover in its closed position; contacts on the fuse-carrier adaptedto engage the terminals in the receptacle respectively, said contactsand terminals being so relatively arranged as to be capable of suchengagement only while the cover is locked closed by said locking means;and a fuse-link connected between said contacts on the fuse carrier.

2. The combination of a receptacle or casing containing a suitable arcvsuppressing liquid; circuit terminals within said receptacle; a coverand fuse carrier for closing the receptacle; interlocking means on thecover and receptacle adapted to be engaged to secure the cover in place;contacts on said fuse-carrier adapted to be engaged with the terminalsrespectivelyY only by relative movement of the cover bringing theinterlocking means into engagement in advance of the engagement of thecontacts g, and a fuse-link connected between'said contacts on thefuse-carrier.

3. The combination of a receptacle or casing containinga suitable arcsuppressing liquid; circuit terminals within said receptacle; a coverand fuse-carrier; a bayonetjoint connection between the receptacle andcover tor locking the latter closed; contacts positioned on saidfuse-carrier to 'be er1- `gaged with the terminals respectively only by.the relatiye rotation of the coverand rel ceptacle servlng to interlockthe parts of. the

bayonet-joint; and a fuse-link connected between said contacts on thefuse-carrier.

il. rThe combination of a receptacle or casing containing a suitable arcsuppressing liquid; a cover for closing the top ot the re ceptacle saidcover havin a carrier depending into the receptacle; interlocking meanson the cover and receptacle adapted to be brought into engagement byrelative rotation thereof; circuit terminals within the receptacle;contacts on opposite sides of the carrier adapted to be engaged with theterminals by said relative rotation which engages the interlockingmeans; and a fuse link bending around the lower end of said carrier andconnecting between said contacts.

5. In an electric fuse, the combination of a fuse-link support, afuse-link secured at two separated points to said support, said link atone or both of said points of anchorage being normally bent butin beingsecured to the support-caused to assume a more straightened position,thereby creating in the link a tension adapted upon rupture of the linkto relatively move away from each other. theV terminals formed by saidrupture.

6. In an electric Jfuse,tl1e combination of a fuse-link support, a`fuse-link secured at its ends to said support in an approximate U-shape,said link at one or both of its ends being normally bent but caused toassume a more straightened position in being secured to the support,thereby creating in the link itself a tension adapted upon rupture ofthe link .to relatively Amove away from each other the terminals formedby said rupture.

In testimony whereof l have signed this specification in the presence oftwo subscribing witnesses.

ROUES lV. DUWNES. Witnesses G. W'. STEERE, K. ltl. GREENE.

